System and method for detection



Oct. 13,

R. H. RINES SYSTEM AND METHOD FOR DETECTION Original Filed June 23, 1943 DETECTOR 76 [MIXER I 82 F l G. 2

- SUPERSONIC /OSCILLATOR mvmon ROBERT HARVEY RINES BY m M flu.

ATTORNEYS United States Patent 3,153,236 YTllvi AND l /iETl-ltll) FGR DETECTKON Robert Harvey Rines, Newton, Mass. ill Broad St., Room 1018, Boston 9, Mass.)

@riginal application June 23, 1943, Ser. No. 492,167, now

Patent No. 2,539,476, dated .lan. 3t}, 1951. Divided and this appli ation Jan. 22, 195i, Ser. No. 297,199

16 Claims. (Cl. 343-1t5) The present invention relates to a system and method for detection, and more particularly to the use of radiofrequency energy for detecting the presence of elastic vibrations in a radio-wave-reflecting medium. This application is a division of copending parent application, Serial No. 492,167, filed June 23, 1943, for System and Method of Communication, now Patent No. 2,539,476, issued January 30, 1951. Y

An object of the invention is to provide a new and improved system and method for detecting submarines.

Other and further objects will be explained hereinafter and will be particularly pointed out in the appended claims.

The invention will now be more fully explained in connection with the accompanying drawing in which FIG. '1 is a diagrammatic view of a preferred apparatus illustrating the reflection of radio Waves from the surface of a body of water that is subjected to elastic vibrations by an underwater submarine, and FIG. 2 is a schematic circuit diagram of a preferred receiving apparatus.

As disclosed in the said parent application, it has been found that if a radio-wave reflecting medium is subjected to mechanical vibrations, such as elastic waves, during the reflection of radio-frequency energy therefrom, the reflected radio-frequency energy will befound to' have become modulated with a modulation frequency of the same periodicity as the mechanical vibrations. This phenomenon is utilized in the present invention for the detection from the air above the water of underwater submarines or other underwater sources that cannot be detected directly by radio waves because of the radio-waveimpervious nature of a water medium.

A submerged, moving submarine 64- is shown in FIG. 1 emitting mechanical elastic-Wave vibrations, sonic and ultrasonic, into the water 66. Radio waves beamed or radiated along a path '70 from, for example, a radar or other system carried by an airplane 68, will strike the surface '72 of the water 66, to be reflected or scattered from regions of the water near the surface '72 along a path '74 back to the airplane 68. Since the surface of the water as well as the submarine constitutes a radiowave reflecting surface that is being subjected to strong elastic vibrations produced by the submarine 6% the reflected or scattered waves traveling along the path 74 will have become modulated by these mechanicalvibrations in accordance with the above-described phenomenon disclosed in the said parent application.

The modulation of the reflected or scattered radio waves produced by the vibrations emitted by the submarine 6 3 may be differentiated from any spurious modulation produced by other well-known sources of vibrations such as, for example, by water-wave motion or by shrimp and other fish as well as organisms in the water, by virtue of the fact that submarines are known to emit distinctive, continuous, very strong, predetermined, relatively highfrequency vibrations outside the vibration frequency specice trum produced by the random motion of water waves and by these various fish and other organisms. Many submarines, for example, are known to produce extremely strong vibrations while in motion in the neighborhood with theantenna 76 for analyzing the received waves may have any desired form such as the form, for'example,

of the circuit shown in FIG. 2. This receivercomprises radio-frequency receiving and demodulating or detecting circuits 89. Any desired detected modulation frequency may, of course, be filtered out. If a'nyultrasonic modulation frequency produced by the submarine 64, for example, is to be detected, the demodulated signal may be fed 1 to a mixing system 82 to which may be supplied a-ditferent ultrasonic frequency from an ultrasonic-frequency local oscillator source 84. Any desired'audio frequency beat signal may thus be produced for indication in a loud speaker 86 or in any other type of .indicator when the submarine is present in the water, thereby to provide an indication of the presence or the absence of the submarine or other source of vibrations in the water. 7

It is to be understood, or course, that the small angle of. incidence and reflection of the transmitted and received paths 7t) and 74- and the shown degree of submersion of the submarine are illustrative only. Propagation of the waves along the surface oftlie" water'between transmitter and receiver may also be utilized.

The direction or location'of the elastic Vibration source, such as the submarine, is that direction and location of j the radio beam in which is detected a maximum modulation etlect upon the radio waves received after reflection and scatter from the water.

Modifications will occur to those skilled in the art and all such are considered to fall within the spirit and scope of the invention as definedin the appended claims.

I \Vhat is claimed is: i

l. A method of detecting under-water submarines that comprises radiating radio waves from a point above the surface of the water to the surface of the water containing a submarine that'is emitting sonic or ultrasonic vibrations, receiving the radio waves reflected or scattered from the surface of the water, and analyzing the received waves to detect sonic or ultrasonic modulationv of the receivedwaves reflected or scattered from the surface of the water in the vicinity of the submarine, thereby to indicate the presence of the submarine. p

2. A method of detecting'under-water submarines that comprises radiating radio waves to the surface of the water containing a submarine that is emitting sonic or ultrasonic vibrations of known frequencies, receiving the radio waves reflected or scatteredfrom the surface of the water, analyzing the received waves'to detect'modulation thereupon of the known sonic or ultrasonic frequencies of vibration of the submarine, and determining the direction in which the reflected or scattered waves contm'ns a maximum of suchmodulatiomthereby to locate the sub.- marine.

'3,l53,236, Fatented Get. 13, 1964' 3. A method of detecting under-water submarines that comprises radiating radio waves from an aircraft to the surface of the water containing a submarine that is emitting sonic or ultrasonic vibrations of known frequencies, receiving in the aircraft the radio waves reflected or scattered from the surface of the water, analyzing the received waves to detect modulation thereupon of the known sonic or ultrasonic frequencies of vibration of the submarine, and determining the direction in which the reflected or scattered waves contains a maximum of such modulation, thereby to locate the submarine.

4. A method of detecting the presence of a source of elastic vibrations of predetermined frequency disposed in a mediurnimpervious to radio waves that comprises radiat ing radio waves to a surface of the radioavave-impervious medium, receiving the radio waves reflected or scattered from the said surface of the medium, and analyzing the received waves to detect a modulation of the predetermined frequency of the received waves, thereby to indicate the presence of the source of elastic vibrations.

5. A system for detecting under-wave submarines having, in combination, means for radiating radio Waves to the surface of the water containing a submarine that is emitting sonicor ultrasonic vibrations of known frequencies, means for receiving the radio waves reflected or scattered from the surface of the water, means for analyzing the received-waves to detect modulation thereupon of the known sonic or ultrasonic frequencies of vibration and means for indicating the detected modulation to indicate the presence of the submarine.

6. The system claimed in claim and in which the angle of incidence and reflection of the radiated and received radio waves is small.

7. A system for detecting under-water submarines having, in combination, means for radiating radio waves along the surface of the water containing a submarine that is emitting sonic or ultrasonic vibrations of known frequencies, means for receiving the radio waves propagated along the surface of the water in the vicinity of the submarine. means for analyzing the received waves to detect modulation thereupon of the known sonic or ultransonic frequencies of vibration and means for indicating the detected modulationto indicate the presence of the submarine.

8. A system for detecting under-water submarines having, in combination, means for radiating radio Waves to the surface of the Water containing a submarine that is emitting sonic or ultrasonic vibrations of known frequencies, means for receiving the radio Waves reflected or scattered from the surface of the water, means for mixing the received waves with local oscillations to produce audio-frequency beat signals thereby to detect the modulation upon the received waves of the known sonic or ultrasonic frequencies of vibration and loud-speaker means for indicating the detected modulation to indicate the presence of the submarine.

9. A system for detecting under-water submarines that comprises means for radiating radio waves from a point above the surface of the water to the surface of the water containing a submarine that is emitting sonic or ultrasonic vibrations, means for receiving the radio waves reflected or scattered from the surface of the water, and means for analyzing the received waves to detect sonic or ultrasonic modulation of the received waves reflected or scattered from the surface of the ocean in the vicinity of the submarine, thereby to indicate the presence of the submarine.

10. A system for detecting under-water submarines that comprises means for radiating radio waves to the surface of the water containing a submarine that is emitting sonic or ultrasonic vibrations of known frequencies, means for receiving the radio waves reflected or scattered from the surface of the water, means for analyzing the received waves to detect modulation thereupon of the iknown sonic or ultrasonic frequencies of vibration of the submarine, and means for determining the direction in which the reflected or scattered waves contains a maximum of such modulation, thereby to locate the submarine.

11. A system for detecting under-water submarines that comprises means for radiating radio waves from an aircraft to the surface of the water containing a submarine that is emitting sonic or ultrmonic vibrations of known frequencies, means for receiving in the aircraft the radio waves reflected or scattered from the surface of the water, means for analyzing the received waves to detect modulation thereupon of the known sonic or ultrasonic frequencies of vibration of the submarine, and means for determining the direction in which the reflected or scattered waves contains a maximum of such modulation, thereby to locate the submarine.

12. A system for detecting the presence of a source of elastic vibrations of predetermined frequency disposed in a medium impervious to radio waves that comprises means for radiating radio waves to a surface of the radiowave-impervious medium, means for receiving the radio waves reflected or scattered from the said surface of the medium, and means for analyzing the received waves to detect a modulation of the predetermined frequency of the received waves, thereby to indicate the presence of the source of elastic vibrations.

13. A system for detecting under-water submarines completely submerged below the surface of the water, having, in combination, means for radiating radio waves to the surface of the water containing a submarine that is emitting sonic vibrations of known frequencies, means for receiving the radio waves reflected or scattered from the surface of the water, means for analyzing the received waves to detect modulation thereupon of the known sonic frequencies of vibration and means for indicating the detected modulation to indicate the presence of the submarine.

14. A method of detection that comprises radiating radio Waves to the surface of a body of water containing a moving propeller and the like that is emitting sonic or ultrasonic vibrations and correspondingly disturbing the water, receiving the radio Waves reflected or scattered from the surface of the water, and analyzing the received Waves to detect sonic or ultrasonic modulation of the received waves reflected or scattered from the water surface in the vicinity of the propeller, thereby to indicate the presence of the same.

15. A method of detection that comprises radiating ratio waves to the surface of a body of water containing a moving propeller and the like that is emitting sonic or ultrasonic vibrations of known frequencies and correspondingly disturbing the water, receiving the radio waves reflected or scattered from the surface of the water, analyzing the received waves to detect modulation thereupon of the known sonic or ultrasonic frequencies of vibration of the propeller and the like, and determinating the direction in which the reflected or scattered Waves contains a maximum of such modulation, thereby to locate the propeller and the like.

16. A method of distinguishing radio-wave reflections from the surface of a body of water that comprises radiating radio waves to the surface of the water containing at a region thereof a moving propeller and the like that is emitting sonic or ultrasonic vibrations of known frequencies and correspondingly disturbing the water at that region, receiving. the radio waves reflected or scattered from the surface of the water, analyzing the received Waves to detect modulation thereupon of the known sonic or ultrasonic frequencies of vibration of the propeller and the like, thereby to distinguish the radio waves received from the said region from those received from other regions of the said surface of the water.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Drake Jan. 8, 1935 Muchow Oct. 22, 1935 5 Beuermann Aug. 20, 1940 Chilowsky Oct. 24, 1944 Budenbom Dec. 23, 1947 Bradley July 4, 1950 King Aug. 22, 1950 10 6 OTHER REFERENCES Reflection of Electromagnetic Waves from Sound Waves, by H. J. Schmitt, Aug. 10, 1959, Technical Report No. 310, Cruft Laboratory Harvard University, Cambridge, Mass. Oflicc of Naval Research AD222886 NR-371-016. ASTIA date Oct. 19, 1959. This publication contains 18 pp. of description and 7 pp. of dWg.; pages 13 to 18 and FIGURE 6 relied upon. 

7. A SYSTEM FOR DETECTING UNDER-WATER SUBMARINES HAVING, IN COMBINATION, MEANS FOR RADIATING RADIO WAVES ALONG THE SURFACE OF THE WATER CONTAINING A SUBMARINE THAT IS EMITTING SONIC OR ULTRASONIC VIBRATIONS OF KNOWN FREQUENCIES, MEANS FOR RECEIVING THE RADIO WAVES PROPAGATED ALONG THE SURFACE OF THE WATER IN THE VICINITY OF THE SUBMARINE MEANS FOR ANALYZING THE RECEIVED WAVES TO DETECT MODULATION THEREUPON OF THE KNOWN SONIC OR ULTRANSONIC FREQUENCIES OF VIBRATION AND MEANS FOR INDICAT- 